To resolve non-ideal characteristic problems such as channel fading and intercode interference in a wireless communications system, a multiple-input multiple-output (MIMO for short) technology and an orthogonal frequency division multiplexing (OFDM for short) technology are widely used. In the MIMO technology, an array gain, multiplexing and diversity gains, and a co-channel interference reduction gain in space can be obtained for a signal by using resources of space dimensions without increasing system bandwidth, so that a communications system capacity and spectral efficiency are improved.
The MIMO technology is classified into low dimensional MIMO and high dimensional MIMO (HD-MIMO for short). An HD-MIMO technology further improves a system capacity by increasing a quantity of antennas at receive and transmit ends.
Currently, a data transmission process based on the MIMO technology includes: partitioning a transport block (TB for short) into multiple code blocks (CB for short), separately performing channel encoding, scrambling, and modulation on each CB, then performing layer mapping processing, and performing precoding processing, resource mapping, and OFDM modulation, so as to generate multiple carriers. In the layer mapping processing step, a data stream is generally mapped to multiple transport layers in a serial-to-parallel conversion manner. Because multiple channels have different transmission characteristics, the generated multiple carriers undergo different fading. After receiving the multiple carriers that undergo different fading, a receive end can restore data sent by a transmit end.
When the prior art is used in a low dimensional MIMO system, after a data stream of a single code word is mapped to multiple transport layers in a serial-to-parallel conversion manner, data of the code word is centrally in a small resource element (RE for short).
If the prior art is used in an HD-MIMO system, data of a code word is mapped to an adjacent RE. A time-frequency channel of the adjacent RE generally falls within coherence time and coherence bandwidth, and it is considered that the channels are nearly unchanged; therefore, enough time-frequency spatial diversity gain cannot be obtained.
It can be learned that, when resource mapping is performed on a code word in the prior art in the HD-MIMO system, a resource to which the code word is mapped has relatively strong coherence; therefore, enough time-frequency spatial diversities cannot be obtained. In this case, a solution is urgently required.